JPH0212939A - Semiconductor wafer transport equipment - Google Patents

Abstract

PURPOSE:To obtain a transfer device which can transfer semiconductor wafers by bringing the centroids of semiconductor wafers into coincidence by providing centroid detection means for movement and control in 3-dimensional directions on the basis of gravity information of a pressure sensor, and transfer means for transferring the centroid of the wafer to the rotation center of a rotary stage. CONSTITUTION:Pressure sensors 43 are so disposed at an equal interval on a raising body 42 as to be located at the vertexes of a regular triangle, received by the gravity of a semiconductor wafer 30 upon rising of the body 42, this gravity information is converted to an electric signal or the like and output. A moving shaft 41 is so displaced that its raising center coincides with the centroid of the wafer 30 on the basis of the gravity information from the sensors 43. A fork 51 is so operated as to transfer the wafer 30 detected at its centroid from the body 42 to a rotary stage 2. Accordingly, after the detected centroid of the wafer 30 is brought into coincidence with the rotation center of the stage 2, the wafer 30 is transferred onto the stage 2.

Description

DETAILED DESCRIPTION OF THE INVENTION [Field of Industrial Application] The present invention relates to an apparatus for transporting a semiconductor wafer onto a rotating stage for spin coating of resist.
In particular, the present invention relates to a transfer device capable of aligning the center of gravity of a semiconductor wafer with the center of rotation of a rotary stage.

[Conventional technology]

In the manufacturing of semiconductor devices, it is necessary to perform multiple steps to apply resist onto semiconductor wafers, and a transport device that transports the semiconductor wafer taken out of the wafer cassette to a rotation stage for spin cording is incorporated into the manufacturing line. There is. A conventional transport device includes a transport belt that transports a semiconductor wafer to the vicinity of a rotation stage, and a transfer member that takes out the transported semiconductor wafer from the transport belt and transfers it onto the rotation stage. The operation of this transport device is such that the semiconductor wafer transported by the transport belt is stopped at a lifted position, and then the transfer member takes out the semiconductor wafer from the transport belt and transfers it onto the rotating stage. The transfer to the rotating stage is performed so that the center of rotation of the rotating stage and the center of the semiconductor wafer coincide, and the rotating stage chucks the semiconductor wafer thus transferred by vacuum suction or the like. The resist is rotated at high speed, and the resist is spin-coded.

[Problem to be solved by the invention]

Incidentally, a semiconductor wafer generally has an orientation tension flat formed therein, and in such a case, the center of gravity shifts due to the portion removed from the orientation tension flat. FIG. 2 shows a semiconductor wafer 30 on which such an ori-nee tension flat 31 is formed, and the center of gravity Gc has moved to the opposite side of the ori-nee tension flat 31 with respect to the center WC of a circle. When spin coding is performed on a semiconductor wafer in which the center of gravity Gc and the circle center We are misaligned, in conventional equipment, in order to align the circle center Wc of the semiconductor wafer with the rotation center of the rotation stage, the semiconductor wafer is aligned with the rotation center of the rotation stage. The centers of gravity of the wafers do not match and rotation becomes unstable. As a result, the resist is not uniformly diffused, and the thickness of the resist film becomes non-uniform.

SUMMARY OF THE INVENTION Therefore, an object of the present invention is to provide a semiconductor wafer transport device that can transport a semiconductor wafer so that the center of gravity of the semiconductor wafer coincides with the center of rotation of the rotary stage in order to ensure stable rotation of the rotary stage.

[Means to solve the problem]

A semiconductor wafer transport device according to the present invention includes a transport means for transporting a semiconductor wafer to a predetermined lifting position, and at least three pressure sensors that receive the gravity of the semiconductor wafer, and lifts and lowers the semiconductor wafer at the lifting position. At the same time, the center of gravity detection means is controlled to move in a three-dimensional direction so that the lifting center coincides with the center of gravity of the semiconductor wafer based on gravity information from the pressure sensor, and the semiconductor wafer whose center of gravity has been detected is removed from the lifted position and rotated. The present invention is characterized by comprising a transfer means for transferring the semiconductor wafer so that the center of gravity of the semiconductor wafer coincides with the center of rotation of the stage.

[Effect]

Since the transfer device according to the present invention is configured as described above, the center of gravity detection means that moves in three-dimensional directions based on information from the pressure sensor aligns the lifting center with the center of gravity of the semiconductor wafer and transfers it. The alternative means operates to align the detected center of gravity of the semiconductor wafer with the center of rotation of the rotation stage.

〔Example〕

Hereinafter, the present invention will be explained in detail based on the accompanying drawings.

FIG. 1 shows a perspective view of a conveying device according to an embodiment of the present invention. A transport means 1 transports a semiconductor wafer 30 taken out from a wafer cassette (not shown), a rotation stage 2 provided near the end of the transport means 1 and performs resist spin coating by high-speed rotation, and a rotation stage 2 for performing resist spin coating on the semiconductor wafer 30 It is configured to include center of gravity detection means 4 for detecting the center of gravity, and means 5 for transferring the semiconductor wafer 30 onto the rotation stage 2.

The conveying means 1 includes two parallel endless conveyor belts 12 that are passed around pulleys 11, and conveys the semiconductor wafer 30 by driving a motor (not shown). This transportation is
As will be described later, the conveyance of the semiconductor wafer 30 is continued until the semiconductor wafer 30 reaches above the center of gravity detecting means 4, which is the lifting position, and the transport of the semiconductor wafer 30 is stopped at the lifting position. For this purpose, an appropriate stopper (not shown) is provided above the conveyor belt 12, and the semiconductor wafer 30 comes into contact with the stopper to stop the conveyance.

The two conveyor belts 12 are driven to run at the same speed to prevent the semiconductor tool 30 from turning during conveyance.

The rotation stage 2 includes a rotation shaft 21 and a rotation disk 22 mounted on the rotation shaft 21. The rotary disk 22 chucks the semiconductor wafer 30 by vacuum suction or the like and rotates the semiconductor wafer 30 at high speed, and is provided above it with a resist nozzle (not shown) for dropping resist. The semiconductor wafer 30 is placed on this rotary disk 22.
Resist is dropped onto the surface and rotated at high speed to diffuse the resist and form a resist film over the entire surface.

Here, three pins 23 are protruded from the rotary disk 22, and these pins 23 operate so as to be pulled into the rotary disk 30 when the semiconductor wafer 30 is placed thereon.

The center of gravity detection means 4 includes a moving shaft 41 and a lifting body 42 supported on the same shaft 41, and is located between the two conveyor belts 12. The center of gravity detecting means 4 lifts the semiconductor wafer 30 whose conveyance has been stopped by the stopper described above from the conveyor belt 12, and also moves up and down so as to lower it onto the conveyor belt 12 from the lifted state.

Further, the center of gravity detecting means 4 is controlled to move in the front and rear and left and right directions within the conveyor belt 12, and performs relative displacement with respect to the semiconductor wafer 30. This displacement is controlled so that the lifting center coincides with the center of gravity of the semiconductor wafer 30, thereby detecting the center of gravity of the semiconductor wafer 30.

Reference numeral 43 indicates a pressure sensor such as a piezoelectric sensor provided on the upper surface of the lifting body 42. This pressure sensor 43 is placed on the lifting body 42 at equal intervals so as to be located at each vertex of an equilateral triangle.
When the lifting body 42 rises, the gravitational force of the semiconductor wafer 30 is applied, and this gravitational information is converted into an electrical signal and output. The moving axis 41 is connected to this pressure sensor 4.
Based on the gravity information from 3, the lifting center is displaced to coincide with the center of gravity of the semiconductor wafer 30.

Therefore, each pressure sensor 43 is connected to a calculation device (not shown), and the drive source (not shown) of the moving shaft 41 is connected to a movement control device (not shown). In such a configuration, the calculation device receives gravity information from each pressure sensor 43, calculates the moving direction and distance of the moving axis 41 so that the gravity values of all pressure sensors 43 are equal, and sends the calculation device to the control device. Output. The movement control means controls the movement of the movement shaft 41 in the front and rear or left and right directions based on the information. Note that if it is necessary to perform the displacement operation by the moving shaft 41 multiple times, after the first displacement is completed, the moving shaft 41 is lowered to place the semiconductor wafer 30 on the conveyor belt 12. The device is driven to release the pressure on the pressure sensor 43, then rise, lift the semiconductor wafer 30 again, detect gravity, and repeat these operations.

The transfer means 5 includes two parallel forks 51 and a drive source (not shown) for driving the forks 51. The fork 51 operates to transfer the semiconductor wafer 30 whose center of gravity has been detected from the lifting body 42 to the rotation stage 2. Therefore, the fork 51 is retracted from the conveyor belt 12 while the center of gravity is being detected by the center of gravity detecting means 4, and after the center of gravity is detected, it advances in the direction of the conveyor belt 12 and lifts the semiconductor wafer 30 on the lifting body 42 from below. Then, the semiconductor wafer 30 is moved horizontally in the direction of the rotary stage 2 to align the detected center of gravity of the semiconductor wafer 30 with the center of rotation of the rotary stage 2, and then the semiconductor wafer 30 is transferred onto the rotary stage 2.

Next, the operation of the above embodiment will be explained.

The semiconductor wafer 30 is lifted up by the transport means 1,
That is, when the semiconductor wafer 30 is transported directly above the center of gravity detection means 4, the transport of the semiconductor wafer 30 is stopped by the stopper. Next, the center of gravity detection means 4 performs a first lift and lifts up the semiconductor wafer 30. As a result, each pressure sensor 4
3 receives the gravity of the semiconductor wafer 30 and outputs the information to the arithmetic device. The arithmetic device calculates the direction and amount of displacement of the center of gravity detection means 4 so that the gravity values of the pressure sensors 43 match, and outputs them to the movement control device.

On the other hand, the center of gravity detecting means 4 is lowered to place the semiconductor wafer 30 on the conveyor belt and is in a standby state. The movement control means controls the movement of the center of gravity detection means 4 in a standby state based on the direction and amount of displacement from the arithmetic device, and then raises the center of gravity detection means 4 again, and the gravity detection means 4 lifts up the semiconductor wafer 30. Thereby, each pressure sensor 43 detects the gravity of the semiconductor wafer 30 and outputs it to the arithmetic device.

If these gravity values are all equal, the center of lifting of the gravity detection means 4 and the center of gravity of the semiconductor wafer 30 are in alignment. If the gravity values are different, the lifting center of the center of gravity detection means 4 and the center of gravity of the semiconductor wafer 30 do not match, and the above-described displacement operation is repeated to make them coincide. After these coincidences have been made, the transfer means 5 takes out the semiconductor wafer 30 from the gravity detection means 4 and moves the semiconductor wafer so that the center of gravity of the semiconductor wafer 30 and the center of rotation of the rotation stage 2 coincide. 83
0 to rotation stage 2.

Therefore, even if the rotation stage 2 rotates at high speed, stable rotation can be ensured, so that a uniform spin code of the resist is possible, and the semiconductor wafer 30 can be stably chucked onto the rotation stage.

The present invention is not limited to the above embodiments, and various modifications are possible.

For example, a roller conveyor, a belt conveyor, etc. may be used as the conveyance means, and the semiconductor wafer may be transferred using vacuum suction force as the transfer means. Also,
Four or more pressure sensors may be provided.

〔Effect of the invention〕

As described above in detail, according to the present invention, the center of gravity of the semiconductor wafer is detected and the center of gravity is moved to match the center of rotation of the rotation stage, so that smooth and stable high-speed rotation is possible. A resist film with a uniform thickness can be formed.

[Brief explanation of the drawing]

FIG. 1 is a perspective view showing a transfer device according to an embodiment of the present invention, and FIG. 2 is a plan view showing an example of a semiconductor wafer. DESCRIPTION OF SYMBOLS 1... Conveyance means, 2... Rotation stage, 4... Center of gravity detection means, 5... Transfer means, 30... Semiconductor wafer, 43... Pressure sensor.

Claims (1)

[Scope of Claims] A transport means for transporting a semiconductor wafer to a predetermined lifting position; and at least three pressure sensors that receive the gravity of the semiconductor wafer, and lifting and lowering the semiconductor wafer at the lifting position and , a center of gravity detection means whose movement is controlled in a three-dimensional direction so that the lifting center coincides with the center of gravity of the semiconductor wafer based on gravity information from the pressure sensor; and removing the semiconductor wafer whose center of gravity has been detected from the lifting position. and a transfer means for transferring the semiconductor wafer so that the center of gravity of the semiconductor wafer coincides with the center of rotation of the rotation stage.